Sorry Cheetach - BI was even less balanced than RTW.
With rules you were talking about most players would take rome, and rome would be dominating. Every barbarian nation would be destroyed - sooner or faster. Some by archers and plumbatriarii, some by meele rush, some by undefeated cav. We tested that with Fireblade - rome was crushing everything.
BTW Bersekers were one of most balanced units into WHOLE TOTAL WAR HISTORY. Extremely powerful when good used (but after 1.6 patch berseker hardly killed plumbatriari into meele only), but expensive, vulverable to missiles, charging and you had to kept them into mandess :).